Electric discharge device



p 1929- L c; BILLOTTE ET AL ELECTRIC DISCHARGE DEVICE Filed Dec. 20, 1926 jizaerzfim Louis C Bil/017e, Edward Lifison,

Patented Sept. 10, 1929.

UNITED STATES LOUIS G. IBILLOT'I'E, 01' REVERE, AND

PATENT. OFFICE.

ELECTRIC DISCHARGE DEVICE.

Application filed December 20, 1926. Serial No. 155,842.

- This invention relates to electrical discharge devices of the type employing ionized gas, and more particularly to rectifiers for alternating current.

Some of the objects of the present invention are to simplify theconstruction of electrical discharge devices of the gas filled type; to increase the eflieiency of operation of said devices; to increase the reliability and uniformity of their operation; to reduce the time required for aging said devices to insure uniform operation; and to lower the impedance of devices of the kind referred to.

In accordance Withone aspect of the present invention, a vessel is filled with an ionizable gas and contains an anode and a cathode having a minimum separation therebetween, preferably of the order of several times the mean free path of electrons in the gas within the vessel and preferably less thanfifty times said path, the maximum separation between the active portions of the anode and cathode being a multiple of the minimum distance therebetween.

By filling the vessel with a gas of the helium group at a temperature in the vicinity of 25 degrees centigrade at a pressure of from 2 to 20 millimetres of mercury, eflicient operating conditions may be obtained when the electrodes are spaced apart in the manner described.

An important feature of the present inven-' tion consists in providing a cathode disk with means at its periphery for controlling the stability, uniformity and intensity of the electrical discharge between the electrodes. An edge of the disk turned up around the electron emitting portion thereof reinforces the disk and holds it in shape during and after high temperature treatment thereof, the edge being so shaped by denting as to control the discharge between the electrodes.

These and other objects and features of the invention will be understood more clearly from the following detailed description in connection with the accompanying drawing, in which:

Fig. 1 is a vertical section of an electrical discharge device, taken on line 11 of Fig. 2; Fig. 2 is a plan of the electrode structure;

'wing mounted at an acute angle therewith;

Fig. 11 is a sectional elevation of a modi- I fication of Fig. 10;

Figs. 12 and 13 are a plan and elevation, re spectively, of a cathode having an auxiliary element to supplement the action of the, oathode; and

Figs. 14 and 15 are a plan and elevation, respectively, of a different modification of the electrode structure.

In Fig. 1, the envelope or vessel 1, of glass,

or other suitable material, contains an ionizable gas, preferably of the helium group, for example argon, helium or neon, or a suitable mixture thereof. The pressure of the gas within the vessel is preferably in the vicinity of from 2 to 20 millimetres of mercury when filled at a temperature in the vicinity of 25 degrees centigrade, but may be somewhat above or below these limits.

The press 2 within the vessel supports the hollow stems 3, one being shown in full elevation and the other in section in Fig. l, the stems being of glass or other suitable electric insulating material. A sleeve 4 of lava, or other suitable refractory insulating material, having its lower end fitting coaxially over the free end of each stem 3, is provided with a constricted portion 5 forming a ledge resting on the free end of stem 3 and adapted for holding the elongate anode wire 6 coaxially therewith. Anode 6 of manganese steel, nickel or other suitable material, has an electron receiving surface 7 at the upper end thereof within sleeve 4 and spaced from the upper end of the sleeve by a distance preferably greater than the mean free path of electrons in the gas in vessel 1. An annular space 8 is preferably provided between the upper or free end of anode 6 and the inner wall of the anode in the sleeve.

A cathode 11, of manganese steel, nickel heat treatment of the disk and of the coating minimum distance therebetween.

sleeve 4, a recess 9 of larger diameter than at the periphery of the' cathode for conspace 8, being provided above the free end of trolling the discharge between the electrodes. It has been found that more uniform or other suitable material, is

[preferably in thereon may be obtained by denting the rim the form of a sheet or plate, an

in the modiat one or more places 18, the effect apparently fication shown as illustrative of the invenbeing to reduce the heating of the peripheral tion, the cathode is inthe form of a disk. portions of the disk in comparison'with the The cathode is preferably of such size in re-' heating when it is not dented, so that the lation to the electrodespacings that the maxperipheral portions are not too strongly heatimum separation between the active portions ed in comparison with the portions nearer the of the anode and cathode is a multiple of the center of the disk.

Cathode The described relation of electrode spac- 11,'is.positioned laterally over sleeves 4 and' ings to the mean free path of electrons in the anodes 7, the disk resting on the ends of the gaseous filling, gives rise to high conductivity sleeves and having a pair of thimbles12 fitbetween one of theelectrodes .6 and electrode ting over the free ends of the sleeves, each 11, when said electrode 6 is positive with refthimble being coaxial with one of the anodes spect to electrode 11 and gives rise to relative- 6. It will be noted that thimbles 12 are ly low conductivity or open circuit conditions formed in the sheet metal of the disk. -In the when the potentials of the electrodes are remodification illustrated by way of example in versed. It is thus possible to efficiently rec- Figs. 1 and 2, the thimbles are connected by tif alternating current. a v a bridge 13 for constructional reasons, so that ents 18 in rim 17 of the disk appear to the two thimblesmay be looked upon as being increase the reliability and uniformity of a single thimble when taken as a whole. A operation of the device. When first starting separate preforation 14, of slightly larger directifying action after completing the conameter than anodes 6, is provided in the disk struction of the rectifier, the dents appear to coaxially over each anode 6. i function in sucha manner as to reduce the I A stay wire 15 sealed into press 2 normal time required to age the rectifier. For exto cathode disk 11 is secured to the disk to hold ample, in certain instances where no dents it from moving axially of anodes 6 and have been provided, several hours of continsleeves 4, the thimbles 12 serving to-hold disk uous operation of the rectifier have been neces- 11 from moving laterally to sleeves 4 so that sar before the action of the rectifier became perforations 14 are retained in coaxial relastabilized so that a uniform current could be tionship with anodes 6. It will be noted that obtained therefrom, Whereas in a rectifier in perforation 14 are positioned centrally in which dents 18 are provided, the necessary disk 11 and symmetrically disposed therein, aging may be accomplished quite consistentthe stay wire 15 being anchored to the center ly within from 30 to seconds, thus greatly of the disk between perforations 14. expediting the manufacture of the rectifiers.

A U shaped channel 16 is spot welded or A further advantage in the use of dents 18 otherwise secured at the bottom of the U to appears to be in localizing the discharge bedisk 11, the arms of the U being spot welded to tween the electrodes and in preventing the hole in disk 11 and the bottom of the U shaped successful operation of rectifiers where nothmember.. This form of construction makes it ing corresponding in function to dents 18 are possible to make adjustment for an variapresent. By localizing the discharge between tions in the dimensions of the electro e structhe electrodes amore intense electron emission ture so that disk 11 may be placed firmly is obtained from'the cathode and consequentagainst the free ends of sleeves 4 and there ly a lower impedance is obtained between a held in place by welding element 16 to wire given pair of electrodes. Owing to the low Obviously wire 15 may be butt welded to impedance of the device, the energy losses are disk 11, it being necessary, however, in such: small and the efliciency is correspondingly cases to trim wire 15 so that it just extends to high. p Y

the bottom surface 'of .disk 11 when welded. Fig. 3 shows an undented cathode rim 19 I The upper surface of disk 11'is preferably which may be employed in place of rim 17 coated with an active electron emitting sub- Fig. 1. Fig. 4 shows an alternative form of stance such for example as the oxides of bacathode rim 20 in which the edge is rolled rium or strontium. An edge or flange 17 is' over inwardly on the electron emitting side turned up around the electron emitting su'rof the cathode disk.

face of the cathode for the purpose of In Figs. 5 and 6 the cathode disk 11, havreinforcing the cathode, particularly during perforations 14 coaxial with anodes G, as ing and after baking the cathode at high in Fig. 1, is provided with su porting wires temperature by a high frequency magnetic 21 welded at opposite ends 0 a diameter of field directed axially of the disk. The the disk bisecting the line between perforaflange 17 constitutes a concentrated means tions 14, wires 21 being anchored to press 2 opposite sides of the wire 15 which pierces a occurrence of discharges whichoften prevent so that disk 11 is held firmly against the upper end of sleeves 4. In order to hold disk 11 from movement laterally to anodes 6 a Wire is welded at each end to one of the wires 21 and extendsaround sleeves 4 in the form of a figure 8 thereby to hold them in fixed position. It will be noted that no rim is provided on the cathode 11 shown in Figs. 5 and 6, but it is tobe understood that rims 17, 19 or 20 shown in Figs. 1, 3 and 4, respectively, may be provided thereon, if desired.

In the form of cathode shown in Figs. 7 and 8, the anodes 6 are mounted in similar relation to that shown in Fig. 1, sleeves 4 being shown schematically by dotted lines. A wing 22 midway between perforations 14 improves the operating characteristics of the rectifier and serves in part to prevent undesired discharges directly between anodes 6.

In Figs. 9 and 10 the cathode disk 11 is related to anodes 6 in a manner similar to that shown in Fig. 1. Wing 23 secured at one edge to disk 11, as by welding, is disposed at an acute angle with disk 11 in such a position as to reach over perforations 14 and thus serves to concentrate the ionized gases near the surface of the cathode. The cathode structure shown in Fig. 11 differs from that shown in Fig. 10 in that a wire like tip 24 is provided fast to wing 23, the free end of the tip being coaxial with anode 6 and spaced slightly above perforation 14 on the opposite side of disk 11 from anodes 6.

Figs'12 and 13 show a modified arrangement somewhat similar to that shown in Fig. 11. A pair of auxiliary tips 25 coaxial with anodes 6 are shaped from a single wire having its central portion 26 welded or otherwise secured to the top of cathode 11. Tips 25 serve to concentrate the heat and ionization near cathode perforations 14 and thus reduce the resistance of the gap between the cathode and anodes.

In Figs. 14 and 15, the parallel wires 27 serve as anodes extending along the active electron emitting surface of cathode 28, which may be hollow as shown, to facilitate baking by high frequency magnetic induction during manufacture. Stems 29 of glass or other suitable insulating material, preferably adapted for withstanding high temperatures, surround the lower ends of anodes 27 and form protecting sleeves which localize the electron receiving area of the anodes to the upper portions thereof. Cathode 28 is pref erably coated with an electron emitting agent such as that-used on cathode 11, Fig. 1. In any of the modifications of the invention, it is to be understood that the usual terminals, not shown, may be provided at the base of the vessel for connection with the electrode leads,

'so that the base of the vessel fits into a socket in well known manner. The

principles disclosed herein in connection wit rectlfiers are cable to various forms of electric discharge devices employing ionizable gaseous substances.

In all of the above electrode structures the spacing of the electrodes is preferably greater than the mean free path of the gas within which the electrodes are immersed, although if desired the electrodes may be separated by distances less than the mean free path of the gas. It is to be understood that any one of the cathode rims 17, 19 or 20, may be employed at the periphery of the cathode disks shown in any of the figures, thereby to stiffen the disks and to control the discharge between the electrodes. V

The structures shown in the various figures, provide electrodes adapted for full wave rectification of an alternating current. Obviously one of the anodes and the corresponding cathode perforation and thimble may be omitted or the circuit of one anode may be left open in order to provide a rectifier of only one half of an alternating current wave.

l/Ve claim:

1. In an electrical discharge device of the gas filled type, an anode, a cathode spaced therefrom and having a turned up edge at the periphery thereof, and means localized on a portion of said edge for controlling the uniformity of. the discharge betweenv said anode and cathode.

2. In an electrical discharge device of the gas filled type, an anode, a cathode spaced therefrom and having a turned up edge at the periphery of the electron emitting portion thereof, said edge being dented in at least one place for controlling the discharge between said anode and cathode.

3. In an electrical discharge device of the gas filled type, an anode, and a cathode spaced thereform and having an electron emitting surface on one side thereof, said cathode having a reinforcing rim turned upon around said surface, said rim having a plurality of dented-in portions spaced apart therein for controllin the discharge between said anode and catho e.

In witness whereof we hereunto subscribe our names this 18th day of December, 1926.

LOUIS O. BILLOTTE. EDWARD LIPSON.

not limited thereto, but are broadly appli 

